1. Field of the Invention
The present invention relates generally to a hinge including a fulcrum for turning movement thereof in the case that two components to be detachably combined with each other are integrally connected to each other, and subsequently, they are disconnected from each other as desired. More particularly, the present invention relates to improvement of a thin-walled hinge of the foregoing type to be integrally molded with the two components.
2. Related Art
A flexible thin-walled hinge including a fulcrum for turning movement thereof in the case that two components to be detachably combined with each other are integrally connected to each other and disconnected from each other as desired is hitherto practically used in various utilization fields in industries.
The flexible thin-walled hinge having the aforementioned structure has advantages that e.g., in the case of a container having a lid attached thereto, a structure employable for a hinge of the foregoing type for allowing the lid to be turnably openably connected to a housing of the container can easily be produced, and moreover, an assembly of the lid and the housing of the container can integrally be molded at a reduced cost on a mass production line by employing an injection molding process. Owing to the foregoing advantages, many flexible thin-walled hinges each constructed in the above-described manner are used for electrical components such as fuse boxes, protectors for wire harnesses or the like in addition to containers each having a lid attached thereto as mentioned above.
In view of the fact that a thin-walled hinge of the foregoing type is alternately subjected to compressive and tensile stresses due to bending and expanding thereof caused as it is opened and closed, it is constructed such that it can satisfactorily stand against the compressive and tensile stresses induced as it is opened and closed, by designing it to have a small thickness so as to maintain the radius of curvature in relatively large when it is bend.
In addition, with respect to a terminal housing, it is already known that a double engagement member is disposed on a main body of the housing via a thin-walled hinge in order to increase an intensity of retaining power to be applied to a terminal primarily engaged with the housing by actuating conventional engaging means. FIGS. 6 to 8 show by way of perspective view the structure of a terminal housing of the foregoing type including a double engaging member.
In the shown case, the terminal housing includes a partition wall 56 at the intermediate part of a housing main body 41 in order to prevent a male terminal 50 from being disconnected from the housing main body 41 in the forward direction, and the partition wall 56 is projected inward of the inner surfaces of a front wall 42a and a rear wall 42b of the housing main body 41. To prevent the male terminal 50 from being vibratively displaced in the housing main body 41, a lower housing main body 43 located below the partition wall 56 is designed to have a small width between a front wall 43a and a rear wall 43b compared with an upper housing main body 42. In addition, the front wall 43a of the lower housing main body 43 located below the partition wall 56 includes a terminal vibrative displacement preventing portion for preventing the male terminal 50 from being vibratively displaced, and the lower end of the terminal vibrative preventing portion is kept open to the outside in the form of an opening portion 46 (see FIG. 8).
A housing lance 47 serving as a primary engagement member for the male terminal 50 is disposed on the inner surface of one of the opposite side walls 42c of the upper housing main body 42, and moreover, engagement protuberances 48 for holding a double engagement member 44 to be described later in the locked state are disposed on the outer surfaces of the opposite side walls 42c of the upper housing main body 42.
The double engagement member 44 is prepared by bending the opposite side plates 44b each having an engagement hole 45 formed therethrough inside of a plate portion 44a of the double engagement member 44 at a right angle relative to the plate portion 44a along the opposite side edges of the latter. In practical use, the double engagement member 44, especially, the upper end part of the plate portion 44a is openably fitted into the opening portion 46 located below the front wall 42a of the housing main body 41 via a pair of thin-walled hinges 49 and a pair of hinge fitting base portions 49a.
The thin-walled hinges 49 are prepared in the form of a pair of rectangular band-shaped pieces each serving to connect the lower end of the front wall 42a to the hinge fitting base portion 49a. Each thin-walled hinge 49 is dimensioned to have a small thickness enough to allow each thin-walled hinge 49 to be deflected with a very low intensity of power without any possibility that opening and closing of the double engagement member 44 are undesirably obstructed. In addition, since each thin-walled hinge 49 has an adequately determined width, there does not arise a malfunction that bending of the thin-walled hinge 49 is achieved concentratively in a certain narrow region. Thus, local breakage of each thin-walled hinge 49 can be prevented regardless of repeated opening and closing operations of the double engagement member 44.
Primary engagement of the male terminal 50 with the terminal housing is achieved by way of the steps of first inserting the male terminal 50 into the main body 41 of the housing in the arrow-marked direction, bringing the opposite projections 52 projecting outside of an electrical contact portion 51 of the male terminal 50 in contact with the lower surface of the partition wall 56 of the housing main body 41, the front wall 43a of the lower housing main body 43 and the rear wall 43b of the same in order to prevent disconnection of the male terminal 50 from the housing main body 41 and vibrative displacement of the male terminal 50, and subsequently, bringing the housing lance 47 projecting from the housing main body 41 in engagement with an engagement hole 54 formed through a base plate 53 of the male terminal 50.
Next, double engagement is achieved by way of the steps closing the opening portion 46 of the housing main body 41 with the double engagement member 44 via the thin-walled hinges 49, bringing the engagement holes 45 formed through the side plates 44b in engagement with the engagement protuberances 48 on the housing main body 41 so as to hold the double engagement member 44 in the locked state, and subsequently, bringing an upper end surface 44c of the plate portion 44a in engagement with the lower surface of one of the projections 52 of the male terminal 50.
With the thin-walled hinges 49 designed in the above-described manner, however, when the opening portion 46 of the housing main body 41 is closed with the double engagement member 44, it is not always assured that they are bent at the central parts as seen in the opening/closing direction, i.e., in the longitudinal direction of the thin-walled hinges 49. For example, as shown in FIG. 7, there arises an occasion that the thin-walled hinges 49 are not bent at the central parts thereof as seen in the longitudinal direction but they are sharply bent at the positions offset away from the central parts. Thus, the fulcrum for turning movement of the thin-walled hinges 49 is dislocated from a predetermined position, causing a radius of turning movement of the thin-walled hinges 49 to vary. This leads to the result that there arises a malfunction that the engagement holes 45 on the double engagement member 44 do not reach the engagement protuberances 48 on the main body 41 of the housing or they pass past the engagement protuberances 48. In view of an occurrence of the foregoing malfunction, a highly trained skill is required for an operator in order to assure that the double engagement member 44 is correctly held on the housing main body 41 in the locked state. In addition, there is existent a certain limit when each of the thin-walled hinges 49 is designed to have a smaller thickness so as to allow them to be easily bent. If each thin-walled hinge 49 is designed to have an excessively small thickness, the strength of the thin-walled hinge 49 is undesirably reduced in excess of a predetermined level.
Therefore, in the case that two components to be detachably combined with each other are integrally connected to each other and disconnected from each other like the thin-walled hinges 49, there appears a problem that each inserting operation can not smoothly be performed when the aforementioned locking mechanism is employed for the thin-walled hinges 49 each including a fulcrum for turning movement thereof. In addition, when the thin-walled hinges 49 are bent at the positions offset away from predetermined ones, breakage is liable to occur at the sharply bent positions. If they are sharply bent while exhibiting an acute angle with the thin-walled hinges 49, operator's fingers are liable to collide against the sharply bent parts of the thin-walled hinges 49, resulting in his fingers being injured with them. Another problem is that the terminal housing exhibits poor appearance due to the presence of the sharply bent parts of the thin-walled hinges 49.
In the case that the double engagement member 44 is connected to the housing main body 41 via the thin-walled hinges 49 like the aforementioned terminal housing, if the thin-walled hinges 49 are sharply bent at the positions offset away from the predetermined ones when the opening portion 46 of the housing main body 41 is closed with the double engagement member 44, a certain intensity of power effective for slantwise raising up the upper end surface 44c of the plate portion 44a is exerted on the double engagement member 44 as shown in FIG. 8, resulting in the upper end surface 44c of the plate portion 44c failing to be engaged with the lower surface of one of the projections 52 of the male terminal 50. Thus, there is a possibility that double engagement can not reliably be achieved with the thin-walled hinges 49 designed in the above-described manner.